Balanced throttle valve for pneumatic tools



May 6, 19.30. R. A. NoRLlNG BALANCED THBOTTLE'VALVE'FOR PNEUMATIC TOOLS Filed Feb. 14, 1927 Patented AMay 6, 1930 UNITED STATES PATENT OFFICE- REINHOLD A. NORLING, or AURORA, ILLINOIS, AssIeNOR 'ro INDEPENDENT PNEU- VYMATIC rroOL COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE BALANCED THROT'ILE VLVE FOR PNEUMA'II TOOLS Appliicationrled February 14,1192?. Serial No. 167,884.

This invention relates to improvements in throttle valve mechanism for pneumatic tools, such as chipping hammers, riveting hammers, etc.

Much trouble has been experiencedin the past with the throttle valve parts rapidly wearingV out` and thus producing ineflicient tools. In a straight throttle valve as heretofore made, the stem and valve member have been made 1n two parts with the stem fitting loosely in a recess in the adjacent end of the valve member. Live air` would get in between the valve member and the stem and exert a pressure to force the stem against the trigger lever with the result' thatthe trigger would rub against the stem in the actuation of the parts, and thus, not only wear out the end 'of the stem and the part of the trigger engaging the same, but also enlarge the hole in the trigger through which the pivot pin c extends to so produce a leaky assembly. A puppet ty e of throttle valve with the beveled seat could e lapped in when it started to leak,

but this type of valve asheretoiore-made would be out of balance when the valve is open, and, as the pressure againsttbe trigger Vwould be equal to the area of the stem multiplied by the air pressure, the pressure f3() against the trigger would cause the same to rub against the end of the valve stem and eifectvrapid wearing of the parts.

The main obj ect of my invention is to pro'- vide a throttle valve of the puppet type and have the valve balanced when open, and thus prevent pressure against the trigger and consequent wear on the parts, thereby overcoming the objections as above noted.

The invention consists further in the construction of my improved valve assembly,

and, as shownV in the drawings- Fig. 1 is a side elevational view of a chipping hammer equipped with a throttle valve mechanism of my invention;

Fig. 2 is an enlarged vertical sectional view through said mechanism and the associated portions of the handle of the tool; Y

Fig. 3 is a horizontal sectional view taken on line 3-3 of Fig. 2; and

Fig. 4 is a vertical sectional view showing another form of my improvedyalve mechamsm.

1 jkTheV tool shown in Fig. 1, has a barrell and a handle 2,these parts being connectedvv Vtogether at their adjacent` ends as usual in tools of this kind. The portion 3 of the handle is grasped by the hand of the koperator when holding the tool, and ycontainsthe throttle vvalve mechanism of my invention. This mechanism controls the supply of compressed or live air to the barrel of the .tool for f reciprocating the hammer piston therein for delivering the'requiredblows tothe chisel or other working implement 4 inserted in the outer endV of the barrel, as in tools of this general character.

AsY shown in Fig. 2, the handle portion 3 is provided with a bore 5 extending vertically therethrough to receive thevalve bushing 6,which has a tight fit in said bore. Said bushingi has a tapered valve seatf7 Atherein about midway between itsl ends,V with the seat facing the lower end of the bushing. A' puppet valve member 8 is located in the bushing-6 below said seat, and cO-operates therewith to control the passage of live air through the bushing through port holes `9, 10 in the bushing on opposite sides of saidseat. The

.valve member 8 has vertically disposed and axially'aligned guide stems 11,12 on opposite sides thereof. Sleeves 13, 14 are located in the bushing 6 on opposite sides of the valve VSeat 7, and the stems 11, 12 are slidably mount- Ved in thesesleeves yso asto guide the valve Y in its movements on and OE its seat. The bore-of the bushing 6 is so made as to hold thel sleeves 13, 14 in axial v alignment and thus maintain the valve member 8 central in the bushing in itsmovements on and ott its seat. The val'vefmember 8 does not have a tight lit in the bushing 6, suiiicient clearance being provided so that the live `air entering the bushingthrough the port holes 9 on the under side of the valve seat 7 may freely flow around the sidesof the valve member 8 to reach the outlet port holes 10 when the valve member is oii' its seat, as shown in Fig. 2. i Thus when the valve member 8 is in its open'po'sitiom-that is, oil' itsseat 7 the air pressure on opposite sides of the valve, that use, that is, closed; and balanced when inuse, that is, open. It prevents pressure against the trigger lever and consequent Wear on the parts. The long sleeve for the upper stem 11 is also an improvement and if worn can be replaced Without replacing the more expensive main bushing 6. In both forms of structure shown, the lower sleeve can also be readily and easily removed. With the form shown in Fig. 2, the threads in the bushing 6 and on the cap need not be accurately machined, and thus the expense of these partsis kept to the minimum.

The details of structure and arrangement of parts shown and described maybe variously changed and modified without departing from the spirit and scope of my invention.

I claim as my invention:

l. A throttle valve mechanism for pneumatic tools, comprising in combination with the handle of the tool having an air supply passage and a bore therein with the bore extending across said passage, of a bushing fitting in said bore and dividing the same into upper and lower chambers in said passage, said bushing having a valve seat therein and air ports extending through said bushing on opposite sides of said seat and opening into the respective chambers, a puppet valve member in said bushingfor said seat and having guide stems on opposite sides thereof and supported through the medium of said bushing, said stems having their outer ends of substantially equal area and exposed to the atmosphere to provide a balanced valve when off said seat, and means for moving the valve member on and o-if its seat.

2. A-throttle valve mechanism for pneumatic tools, comprising in combination with the handle of the tool having an air supply passage and a bore therein with the bo-re extending across'said passage, of a bushing litting within said bore and dividing the same into upper and lower chambers in said passage, said bushing'having a valve seat therein and air ports extending through the bushing on opposite sides of said seat and opening into the respective chambers, a puppet valve member in said bushing for said seat and having guide stems on opposite sides thereof and supported through the medium of said bushing, said stems having their outer ends of substantially equal area and exposed to theatmosphere to provide a balanced valve when olf said seat, Vsaid valve having its portion on the inlet side of said seat fitting within said bushing so as to uncover the ports on such side vof the seat in succession as the valve member is moved off of its seat, and means fork moving the valve member on and off its seat.

3. A throttle valve mechanismV for pneumatic tools, comprising in combination with the handle of the tool having an air supply passage and a bore Vtherein with the bore extending across said passage, of a bushing t-V in between its ends and air ports extending through the bushing on opposite sides of said seat and opening into the respective chambers, l

sleeves removably tted in the bushing on opposite sides of said seat and held in axial Y alignment by said bushing, a puppet valve member in the bushing for said seat and having-guide stems slidably mounted in and supported by said sleeves, said stems having their outer ends of substantially equal area and exposed to the atmosphere, and means for moving the valve member on and ofl' its seat.

4; A throttle valve mechanism for lpneumatic tools, comprising a vertically disposed bushing having a valve seat therein between its ends, upper and lower sleeves removably fitted in the bushing on Vopposite sidesof said seat and held in axial alignment by said bushing, a puppet valve member in the bushing for said seat and having guide stems slidably mounted in said sleeves, a cap made separate from the lower-sleeve and screwed into the lower end of the bushingV to close the same, said cap having a vent holeto expose to the atmosphere the end of the stem in the lower sleeve, said` lower sleeve having a reduced lower end with a loose fit in said cap and providing a shoulder to seat thereon, a spring for holding the lower sleeve seated on said cap and for closing the valve member on its seat, and a pivoted trigger lever engaging the upper stem for moving the valve 0E its seat.

5. The combination with a handle for a pneumatic'tool having an `air supply passage therein with a vertically disposed bore extending across the same, of a bushing fitted in said bore and having a tapered valve seat therein with air ports on opposite sides of said seat and communicating with the portions of the passage as divided by the bushing, upper and lower sleeves fitted in said bushing on opposite sides of said seat, a puppet valve member for said seat and having guide stems on opposite sides thereof and slidably supported in said-sleeves, a cap closing the lower end ofthe bushing and having a vent hole therein to expose to the atmosphere the end of the stem in the lower sleeve, the upper end of the stem in the upper sleeve being exposed to the atmosphere through the upper end of said bore, and a trigger lever pivoted to the handle at one side of the bore and having a lug engaging the top end of the upper stem for moving the valve oli its seat, and a spring surrounding the lower stem for holding the lower sleeve 'against the cap and for moving the valve member to its seat.

In testimony whereof I aiiix` my signature this 8th day of February, 1927.

REINI-IOLD A. NORLING. 

